I. V. Dziublyk, O. P. Trokhimenko, S. O. Soloviov, G. L. Gumeniuk, O. Ya. Dziublyk, N. I. Gumeniuk, O. K. Yakovenko Abstract The aim of the study is a preclinical evaluation of the antiviral activity of aminocaproic acid (ACA) against the prototype strain IBV (Infectious bronchitis virus) of Coronavirus family in vitro. Material and methods. During the research, modern methods were used to determine the cytotoxic effect of the evaluation on a monolayer of BHK-21 cell culture in vitro; cultivation, accumulation and determination of the infectious titer of IBV by cytopathic action on a monolayer of cell cultures; assessment of the antiviral effect of the drug — the establishment of the inhibitory concentration and the chemotherapeutic index (CTI) of ACA in various modes of drug administration: 2 hours before infection, simultaneously with infection and 2 hours after infection. Results. With the introduction of ACA 2 hours before infection, a decrease in the infectious titer of the IBV virus was not established. The antiviral activity of ACA was detected when the drug was added in 2 modes: simultaneously and 2 hours after infection. The introduction of ACА into the medium for cell cultivation at non-toxic concentrations of 7.91–15.82 mg / ml led to a decrease in the infectious titer of the virus by 1.4–2.0 lg TCD50 / 0.1 ml. The CTI of the ACA was 6 in the indicated concentrations and modes, which is an indicator of its promising potential for further studies of antiviral activity in vivo, including clinical studies. Conclusions. The direct antiviral effect of ACA against the prototype H-120 virus strain from the Coronaviridae family in vitro was revealed. The suppression of viral reproduction with an established low toxicity of the drug, a decrease in the infectious titer of IBV by 1.4–2.0 lg TCD50 / 0.1 ml and with a CTD equal to 6.0, indicate the prospects for further study of the antiviral properties of ACA in clinical trials. Key words: aminocaproic acid, coronavirus, antiviral activity.